Checks · Chapter 17
Checks
Nobody writes the checks in nexbrand by hand. They are computed from the version, afresh each time, in the editor while you type. The tab Checks shows them together; the number beside it counts the serious hints.
The hints
| Hint | When |
|---|---|
| White on a colour | white is in the palette and does not reach 4.5:1 on a colourful colour; serious below 3:1. Where it can, nexbrand names the text colour that works better. |
| Large text only on a ground, or nothing reads | no colour of the palette reaches 4.5:1 on that ground, or not even 3:1 |
| Main colour as text | the main colour does not reach 4.5:1 on a light neutral |
| nearly the same | two colours lie less than ΔE 4 apart (CIEDE2000) |
| Green blindness, red blindness | two colours at least ΔE 15 apart normally move closer than ΔE 10 when simulated; neutrals left out |
| Logo | lettering or mark of a drawn word mark below 3:1 to its ground |
| Body text | smaller than 16 px |
| In-house font, system font | for information only: by name only outside, or a fallback is missing |
| Rules, dark mode | see Rules and Dark mode |
When there is nothing, it reads: “Nothing found: every pair, logo and size passes.”
Contrast of every pair
Below the hints stands a table: the row is the text, the column the ground. Each cell carries a grade: AAA, AA, large only or fails. The switch Large text (from 24 px) changes the measure. A click on a cell shows a text sample and the criteria: body text AA 4.5:1, AAA 7:1, large text AA 3:1, graphics and symbols 3:1. The table needs at least two colours.
How others see the palette
Below, five tabs show the palette as it is meant and as it comes across: Typical vision, Green blind, Red blind, Blue blind and Greyscale. A line beneath names pairs that are hard to tell apart. The maths follows Machado, Oliveira and Fernandes (2009) at full strength. Blue blindness is rare; it shows here in the display, but not as a hint in the list.
Computed exactly
Ratios are cut, never rounded up: 4.4992 becomes 4.49. So whatever stands at or above a threshold has reached it. The server and the interface compute the same checks, and programs get them as a list through the API. They do not appear on public pages.
Pavo saysHints are not bans. A pair that is too faint may be perfectly fine for a large heading; then record that in a rule.